    [Patent Document 1] JP-A-8-326758    [Patent Document 2] JP-A-2004-263773    [Patent Document 3] JP-A-2004-225754
A strut-type suspension used for a front wheel of a four-wheeled vehicle has a structure in which a strut assembly incorporating a hydraulic shock absorber in an outer cylinder integrated with a main shaft is combined with a coil spring. Among such suspensions, there is a type in which when the strut assembly rotates together with the coil spring in the steering operation, the piston rod of the strut assembly rotates, and a type in which the piston rod does not rotate. In either type, there are cases where, instead of a rolling bearing, a synthetic resin-made thrust sliding bearing is used between a mechanism for mounting the strut assembly to the vehicle body and a sheet metal-made upper spring seat member which receives one end of coil spring in order to allow a smooth rotation of the strut assembly.